Ellison Taylor J, Ellison Courtney K
Department of Microbiology, University of Georgia, Athens, GA.
bioRxiv. 2024 Jun 6:2024.06.06.597730. doi: 10.1101/2024.06.06.597730.
Bacteria take up environmental DNA using dynamic appendages called type IV pili (T4P) to elicit horizontal gene transfer in a process called natural transformation. Natural transformation is widespread amongst bacteria yet determining how different factors universally contribute to or limit this process across species has remained challenging. Here we show that the most naturally transformable species, is highly transformable due to its ability to robustly bind nonspecific DNA via a dedicated orphan minor pilin, FimT. We show that, compared to its homologues, FimT contains multiple positively charged residues that additively promote DNA binding efficiency. Expression of FimT in a closely related pathogen is sufficient to substantially improve its capacity for natural transformation, demonstrating that T4P-DNA binding is a rate-limiting step in this process. These results demonstrate the importance of T4P-DNA binding efficiency in driving natural transformation, establishing a key factor limiting horizontal gene transfer.
细菌利用称为IV型菌毛（T4P）的动态附属物摄取环境DNA，以在一个称为自然转化的过程中引发水平基因转移。自然转化在细菌中广泛存在，但确定不同因素如何普遍促进或限制跨物种的这一过程仍然具有挑战性。在这里，我们表明，最容易发生自然转化的物种具有高度的转化能力，这是由于它能够通过一种专门的孤儿小菌毛蛋白FimT强有力地结合非特异性DNA。我们表明，与它的同源物相比，FimT含有多个带正电荷的残基，这些残基累加起来促进DNA结合效率。在一种密切相关的病原体中表达FimT足以显著提高其自然转化能力，这表明T4P-DNA结合是这一过程中的限速步骤。这些结果证明了T4P-DNA结合效率在驱动自然转化中的重要性，确立了限制水平基因转移的一个关键因素。
